1. Field
This document relates to a liquid crystal display, and more particularly, to a liquid crystal display which can be made slim while incorporating an illuminance sensor.
2. Related Art
In general, the scope of application of liquid crystal displays has widened due to the lightweight, thinness, and low power consumption of liquid crystal displays. According to this trend, liquid crystal displays are widely used in office automation machines and audio/video machines. The intensity of light beam is adjusted in accordance with a video signal applied to a plurality of control switches arranged in a matrix in order to display a desired picture on a screen.
Since such LCDs are non-emissive devices, the LCDs generally need a light unit such as a backlight unit. A light source for the backlight unit can include fluorescent lamps such as external electrode fluorescent lamps (EEFLs) and cold cathode fluorescent lamps (CCFLs), or a plurality of light emitting diodes (LEDs).
When using the fluorescent lamps as the backlight, device characteristics of the LCD may be easily deteriorated due to the high power consumption and high heat generation of the fluorescent lamps. In addition, the fluorescent lamps generally have a stick shape, so they do not withstand impacts well and can easily break on impact.
However, when the light emitting diodes are used as the backlight, since each light emitting diode is a semiconductor device, the lifetime of the LCD can be long, the lighting speed of the LCD can be fast, and the power consumption of the LCD can be low. The light emitting diode also withstands impacts well and miniaturization thereof is easy. Because of these benefits, there is an increasing trend that light emitting diodes are used in monitors having middle or large sized LCDs such as in computers or television sets, as well as in small sized LCDs such as in mobile telephones, as a light source.
Recently, there have been proposed LCD control methods in which the range of luminance of a displayed image can be enlarged by adjusting the brightness of the backlight and the gamma characteristics of output data. In these control methods, an illuminance sensor is mounted in a liquid crystal module to sense the illuminance of external light. Based on this sensing information, if the external illuminance is high, the amount of electric current supplied to the backlight is increased and the gamma characteristics of output data are increased, while if the external illuminance is low, the amount of electric current supplied to the backlight is decreased and the gamma characteristics of output data are lowered. By this, the power consumption of the backlight can be reduced, and the visibility for users can be greatly improved.
FIG. 1 is a schematic view of an illuminance sensor according to the related art.
As shown in FIG. 1, a conventional illuminance sensor 20 is generally manufactured in a package 24 type so that a sensor portion 26 can be easily exposed to the external light, and then mounted in a printed circuit board 22 (hereinafter, “PCB”).
FIG. 2 shows a mobile phone which employs the illuminance sensor of FIG. 1.
As shown in FIG. 2, the mobile phone having an illuminance sensor 20 mounted in a PCB, senses external light through a hole 32, and adjusts the brightness of the backlight and the gamma characteristics of output data based on the sensed external light. However, in the case that a package type illuminance sensor is mounted in a PCB as seen in FIG. 1, it is necessary to provide much additional space for the mounting area of the illuminance sensor, which makes it difficult to produce slim liquid crystal displays, e.g., for use in mobile phones.
Moreover, the conventional liquid crystal display having a package type illuminance sensor mounted in the PCB has other disadvantages in that, because of spacing distances between the illuminance sensor and a driving integrated circuit (hereinafter, “driving IC”) and between the illuminance sensor and a driving portion, additionally long wiring is needed in order to link or transmit the sensing information from the illuminance sensor to the driving IC and the backlight driving portion. This can complicate the configuration of liquid crystal displays, increase the cost of manufacturing liquid crystal displays, and limits manufacturing of slim liquid crystal displays.